Current sensing comparators are widely used in buck and boost converters. Their function is to detect that current has exceeded a maximum current limit or that the current has changed polarity.
However a current sensing comparator will have an inherent offset and delay that mean the comparator will tend not to change state at the correct moment. These offsets and delays can be compensated for by adding a fixed offset to the comparator threshold level. However, even this compensation is not ideal, because the ideal value of the comparator offset is affected by random process mismatch, inductor value and input or output voltage variation. Therefore a fixed comparator offset will not be able to track the ideal value.
This problem is exacerbated by industry trends for ever smaller inductor values which mean that inductor current fluctuates at greater frequencies.
It is therefore desired to improve the calibration of continuous comparators.